1. Field of the Invention
Included is a spinning cell for a synthetic fiber such as spandex. The spinning cell includes a top closure which reduces or eliminates solvent vapor transfer, where solvent vapor process gas(es) may leave the cell and room air may be introduced into the spinning cell.
2. Summary of the Related Technology
Synthetic fiber may be prepared from a variety of processes including melt-spinning and dry-spinning. Dry-spinning of fiber such as spandex may be achieved by preparing a solution of a polymer such as a segmented polyurethane. The solution is then dry-spun through spinneret orifices in a spinning cell to form filaments. Upon emergence from the spinneret, the filaments are forwarded through a chamber of the cell, in which the solvent is evaporated from the filaments by the introduction of hot gases. The filaments may be coalesced and adhered to each other to form a unitary thread; alternatively, threads may be prepared from single filaments. The thread is forwarded from the cell to a windup where it is formed into a yarn package.
When the hot gas includes oxygen, the risk exists that the solvent may ignite. In order to reduce this risk, care is taken to maintain a low concentration of solvent in the cell. This is achieved by forcing large quantities of gas into the spinning cell.
In order to minimize the risk of fire, the gas in the cell may be an inert gas such as nitrogen or carbon dioxide. A closed loop system in which the evaporated solvent is separated from the inert gas and the inert gas is recycled back to the spin cell is often used to reduce operating costs associated with supplying an inert gas to the spin cell. One difficulty with using an inert gas is sealing the spinning cell from the introduction of air into the spinning cell during cell operation and during cleaning/replacement of the spinnerets without purging the cell of solvent vapors and interrupting the gas flow through the spinning cell. When the spinning cell is sealed to prevent the introduction of air, another benefit is that the operator of the cell will have a reduced exposure to the solvent or process gas used in the spinning process.
Many spinning cells are used today which use air instead of an inert gas. These spinning cells frequently have open top and bottom portions through which air is introduced into the spinning cell and through which solvent vapor and process gases may escape. During production interruptions to exchange spinnerets, it is common practice for the flow of drying gas to be maintained through the spinning cell and these cell openings to be open to the manufacturing areas. During the spinneret exchange, there is potential for the drying gas to escape to the surrounding manufacturing area and/or for room air to be drawn into the spin cell. If the spin cell is supplied from a common, closed loop inert gas supply system the oxygen content of the closed gas system could reach hazardous levels if too much room air is drawn into the cell during this operation. Alternatively, excessive release of inert process gas to the manufacturing area will result in increased operating cost to replenish the loss and risk exposing operating personnel to excessive amounts of inert gas. During production interruptions to exchange spinnerets, it is common practice for the flow of drying gas to be maintained through the spinning cell and these cell openings to be open to the manufacturing areas. During production interruptions to exchange spinnerets, it is common practice for the flow of drying gas to be maintained through the spinning cell and these cell openings to be open to the manufacturing areas.